Direct/indirect luminaire systems and methods

ABSTRACT

A luminaire includes a housing, a downlight that includes one or more first light sources configured to emit a first light downwardly from the housing, a waveguide, and one or more second light sources. The waveguide is formed of a portion of an optical material and characterized by opposing planar faces joined by one or more edge faces about a periphery of the optical material. The waveguide forms at least a portion of an uppermost optical surface of the luminaire. The one or more second light sources are coupled with the housing and configured to emit a second light into the optical material through at least one of the one or more edge faces. The waveguide is configured to emit at least a portion of the second light upwardly from an upper one of the planar faces.

BACKGROUND

Luminaires, or light fixtures, may be designed to meet goals such asemitted light distribution, power consumption, cost, size, and visualaesthetics. Certain luminaires provide direct and indirect light. Suchluminaires typically emit a portion of light downwardly for directlighting of an illuminated area, and another portion upwardly to reflectfrom high surfaces such as walls and/or a ceiling. A portion of theupwardly emitted light that scatters from the high surfaces providesadditional light to the illuminated area. It also provides the aestheticbenefit of making the overall illumination feel more natural, bymitigating the high contrast of the downwardly emitted light againstdark upper surfaces.

SUMMARY

In one or more embodiments, a luminaire includes a housing, a downlightthat includes one or more first light sources configured to emit a firstlight downwardly from the housing, a waveguide, and one or more secondlight sources. The waveguide is formed of a portion of an opticalmaterial and characterized by opposing planar faces joined by one ormore edge faces about a periphery of the optical material. The waveguideforms at least a portion of an uppermost optical surface of theluminaire. The one or more second light sources are coupled with thehousing and configured to emit a second light into the optical materialthrough at least one of the one or more edge faces. The waveguide isconfigured to emit at least a portion of the second light upwardly froman upper one of the planar faces.

In one or more embodiments, a method of lighting an area with asuspended luminaire includes providing a luminaire that includes ahousing, first and second light sources, and a waveguide that forms atleast a portion of an uppermost optical surface of the luminaire. Thewaveguide is formed of a portion of an optical material andcharacterized by opposing planar faces joined by one or more edge facesabout a periphery of the optical material. The method also includesemitting a first light downwardly from the first light source, emittinga second light, from the second light source, into one or more of theedge faces of the waveguide, and scattering at least a first portion ofthe second light upwardly from the waveguide, through an upper one ofthe planar faces.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are described in detail below with reference to thefollowing figures.

FIG. 1 schematically illustrates a space that is illuminated by adirect/indirect luminaire, according to one or more embodiments.

FIG. 2 is a schematic cross-sectional view of a prior artdirect/indirect luminaire.

FIG. 3 is a schematic cross-sectional view illustrating adirect/indirect luminaire, according to one or more embodiments.

FIG. 4 is an exploded schematic view of the luminaire of FIG. 3.

FIG. 5 is a schematic cross-sectional view illustrating anotherdirect/indirect luminaire, according to one or more embodiments.

FIG. 6 schematically illustrates a direct/indirect luminaire thatincludes a waveguide with upward protrusions, according to one or moreembodiments.

FIG. 7 schematically illustrates a direct/indirect luminaire thatincludes a waveguide having outward protrusions that extend through ahousing, so as to emit a portion of light outwardly therefrom, accordingto one or more embodiments.

FIG. 8 schematically illustrates a direct/indirect luminaire thatincludes a waveguide with outward protrusions, and a housing with upperhousing surfaces, according to one or more embodiments.

FIG. 9 schematically illustrates a direct/indirect luminaire thatincludes an optic, according to one or more embodiments.

FIG. 10 schematically illustrates another direct/indirect luminaire,according to one or more embodiments.

FIG. 11 schematically illustrates a direct/indirect luminaire includinga waveguide that obtains light from a downlight source, and redirects aportion of the light to provide uplight, according to one or moreembodiments.

DETAILED DESCRIPTION

The subject matter of embodiments of the present invention is describedhere with specificity to meet statutory requirements, but thisdescription is not intended to limit the scope of the claims. Theclaimed subject matter may be embodied in other ways, may includedifferent elements or steps, and may be used in conjunction with otherexisting or future technologies. This description should not beinterpreted as implying any particular order or arrangement among orbetween various steps or elements except when the order of individualsteps or arrangement of elements is explicitly described. Each exampleis provided by way of illustration and/or explanation, and not as alimitation. For instance, features illustrated or described as part ofone embodiment may be used on another embodiment to yield a furtherembodiment. Upon reading and comprehending the present disclosure, oneof ordinary skill in the art will readily conceive many equivalents,extensions, and alternatives to the specific, disclosed luminaire types,all of which are within the scope of embodiments herein.

In the following description, positional terms like “above,” “below,”“vertical,” “horizontal” and the like are sometimes used to aid inexplaining and specifying features illustrated in the drawings aspresented, that is, in the orientation in which labels of the drawingsread normally. These meanings are adhered to, notwithstanding that theluminaires herein may be mounted to surfaces that are not horizontal.When light is said to be emitted “downwardly” at least most of suchlight is emitted across one or more angles that are below horizontalwhen a luminaire is oriented as shown in the drawings; such anglesinclude nadir, but are not limited to nadir. Similarly, when light issaid to be emitted “upwardly” at least most of such light is emittedacross one or more angles that are above horizontal when a luminaire isoriented as shown in the drawings; such angles include zenith, but arenot limited to zenith.

Certain embodiments herein provide direct/indirect luminaires that emitlight from a waveguide to provide indirect light. These embodiments aredesigned in appreciation of the fact that use of a waveguide to providethe indirect light can provide manufacturing, economic, installation,safety, compact size, and/or aesthetic advantages. Downlight portion(s)of these luminaires typically provide direct light from first lightsources by refracting and/or reflecting light from first light sourcesso the direct light is emitted generally downwardly. Uplight portion(s)of these luminaires use second light sources to produce light thatcouples into one or more waveguides. The waveguides provide indirectlight by emitting the light from the second light sources generallyupwardly. Certain other embodiments tap a portion of light from firstlight sources that primarily provide downlight, into a waveguide thatemits some of the light as uplight.

FIG. 1 schematically illustrates a space 1 that is illuminated by adirect/indirect luminaire 100. Within space 1, an exemplary piece offurniture 5 presents an area 7 where direct lighting might be desired.Direct/indirect luminaire 100 is suspended by one or more cables 110from ceiling 6 of space 1. Direct/indirect luminaire 100 provides bothdirect light 101 that illuminates area 7, and ambient light 102 thatalso illuminates much of space 1, by reflecting from ceiling 6. Itshould be understood that the boundaries illustrated for both directlight 101 and ambient light 102 are only suggested by the lines shown;such boundaries may vary in size or position, and may not be sharpboundaries at all but rather indicate the general location of diffuse orgradient boundaries.

FIG. 2 is a schematic cross-sectional view of a prior artdirect/indirect luminaire 50. Aspects of the direct/indirect luminairesdisclosed herein are based at least in part on an appreciation ofcertain issues related to luminaire 50, as now discussed.

Luminaire 50 includes a housing 51, a first light source 52, a secondlight source 53, first optics 54 and second optics 55. Light sources 52and 53 are typically the same as one another, and optics 54 and 55 aretypically the same as one another. However, each corresponding set oflight source and optics typically generates a light distribution thatresults in an appearance of light being very concentrated, as if from apoint source (or nearly a point source, depending on the type of lightsource 52, 53). That is, optics 54 or 55 may either concentrate orspread a far field distribution of light from the light source 52 or 53with which it is associated, but optics 54 and 55 typically do notspread the near field distribution, so as to spread the appearance ofthe corresponding light source 52 or 53 to which it is attached, over alarger area than is occupied by the light source 52 or 53 itself. Thiscan make it difficult to look directly at luminaire 50, due to a highintensity of light at the image of light source 52 or 53. When luminaire50 is overhead, a natural human aversion response is not to lookstraight up into light source 52 (just as humans tend not to look upinto the sun during the day). However, this aversion response may not beas effective in preventing discomfort in viewing a light source 53 whena viewer is located above a suspended luminaire 50. For example, aviewer may view luminaire 50 from above when the viewer is located on anupper floor or balcony adjacent to an atrium where luminaire 50 isdeployed at a lower level within the atrium, causing discomfort if thenear-field distribution concentrates an origin of the uplight within asmall emitting area. The near field distribution of the uplight can bespread by using diffusing optics, but this solution incurs a cost inefficiency, that is, diffusing optics typically absorb some light whilediffusing the rest, reducing net light output and increasing heatgenerated by luminaire 50.

Wires 56 that provide electrical power to light sources 52 and 53typically couple with (or are routed adjacent to) one or more cables 57from which housing 51 is suspended. Optical and/or aesthetic issuesarise related to cables 57 (and/or 58, as discussed below). Upwardlyemitting light source 52 and associated optics 54 are typicallyapproximately centered within housing 51. Distribution of indirect lightprovided by the upwardly emitting light source 52 favors leaving a spaceopen directly above the associated optics 54 (e.g., an optical axis oflight source 52 and optics 54). However, when luminaire 50 is suspended,housing 51 will be pulled by gravity so as to place cables 57 in thespace that is advantageous to leave open. Thus, especially when optics54 provide a near field distribution of light from light source 52 as apoint source or nearly so, cables 57 will generally cast undesirableshadows upward onto adjacent ceiling and/or wall surfaces.

FIG. 2 also shows a retaining device 59 that pulls cables 57 together ata distance above housing 51, with one or more cables 58 runningvertically upward from retaining device 59. A device like retainingdevice 59 is often used to improve the appearance of luminaire 50 overthat of a luminaire that uses two cables 57 that each run upwardly fromhousing 51 for a considerable distance. In another embodiment, retainingdevice 59 may join cables 57 so that only a single cable 58 would runfurther upward. However, devices like retaining device 59, and cable(s)58 running upward therefrom, can create distracting shadows directlyalong an optical axis of light source 52 and optics 54.

Other aspects of luminaire 50 may be of concern, especially aspectsrelated to light source 52. For example, both light sources 52 and 53will generate heat, yet they are positioned close to one another suchthat the generated heat is within a comparatively small portion ofluminaire 50, which may present a challenge for heat dissipation. If adiffuser is used with light source 52 to spread upwardly directed light,it will typically incur an optical inefficiency on the order of 5% to15%, that is, the corresponding amount of light will be lost, turninginstead into heat. Also, a top surface of optics 54 is typicallyconcave. A concave top surface may be difficult to clean, and maycollect dust or debris, which may present a fire risk.

FIG. 3 is a schematic cross-sectional view illustrating adirect/indirect luminaire 150 that addresses many of the concernsdiscussed above with respect to luminaire 50. Luminaire 150 includes ahousing 151, and a first light source 152 and first optics 154 thatprovide a first light as direct light (e.g., downlight) emitteddownwardly from luminaire 150. Indirect light (e.g., uplight) issupplied by second light sources 162 that are mounted with one or morecircuit boards (e.g., printed circuit boards, or PCBs) 164. In FIG. 3,housing 151 and luminaire 150 are cylindrical, but this is not required;in other embodiments, direct/indirect luminaires may have other shapes(e.g., ovals, cuboid/rectilinear shapes and the like) while using theteachings herein.

First light source 152 and first optics 154 may be substantially similarto first light source 52 and first optics 54 of luminaire 50. PCB(s) 164may be one or more flexible circuit boards that couple with an innersurface of housing 151. PCB(s) 164 may include electrical componentsthat act as power supplies and/or control devices for light sources 162and/or 152; alternatively, power provided to light sources 162 and/or152 may be provided and/or controlled externally to luminaire 150 (e.g.an external switch may control electrical power provided to luminaire150 by an external power supply, LED drivers and the like). Lightsources 162 may be, for example, light emitting diodes (LEDs) in eitherpackaged form, or LED chips mounted directly to PCB(s) 164. Lightsources 162 emit light that couples into a waveguide 160 that forms atleast part of an uppermost optical surface of luminaire 150. Herein,“uppermost optical surface” means the uppermost surface thatsubstantially interacts with light being emitted upwardly, that is, afurther transparent cover would not be considered an uppermost opticalsurface. Light sources 162 need not be identical in color and/or colortemperature, because waveguide 160 will act as a mixing chamber to blendthe light received, as discussed further below.

Waveguide 160 is a planar portion of an optical material (e.g., glass,acrylic, polycarbonate, other plastics, silicone) with opposing planarfaces 161 and 163 joined by one or more edge faces 167 about a peripheryof the optical material. The light that couples into waveguide 160enters through one or more of edge faces 167, and the light issubstantially retained in waveguide 160 through total internalreflection, except for locations where total internal reflection doesnot occur. One mechanism that can defeat total internal reflection atspecific locations is when the light interacts with optional scatteringfeatures 166 that may be part of, or formed upon, a lower planar face ofwaveguide 160. Light scattered by scattering features 166 then typicallyscatters into high angle rays that are not contained by total internalreflection, but are instead emitted from upper face 161 of waveguide160. Some light scattered by scattering features 166 may scatterdownwardly from waveguide 160, so an optional reflector 168 can be addedto reflect such light back upwards to be emitted upwardly from waveguide160.

Thus, a very large portion of the light that is emitted into waveguide160 emits upwardly from housing 151 and luminaire 150. For example,because total internal reflection is a very optically efficientmechanism for distributing light across an area, and if downwardlyscattered light is reflected upwards from optional reflector 168, thenet optical efficiency of the uplight portion of luminaire 150 will behigher than an arrangement that uses a diffuser to distribute light(e.g., light source 52 discussed above).

The emitted uplight originates across the area of waveguide 160, so thatin some embodiments, the light is characterized as having a visuallyappealing light distribution of a uniform area source. Distribution oflight scattering features 166 can be provided so as to provide more orless light scattering at specific areas; for example, few lightscattering features 166 might be provided near light injection edges ofwaveguide 160 where internal light density is greatest, and many lightscattering features 166 might be provided further away from the lightinjection edges of waveguide 160. This arrangement of light scatteringfeatures 166 would provide more uniform light emission across waveguide160 than if light scattering features 166 were uniformly distributedacross waveguide 160. This may be advantageous when luminaire 150 isinstalled at a height where some might view it from its upper side, forexample as a suspended luminaire in an open atrium with some viewinglocations available from upper floors that open to the atrium.

Another mechanism that can defeat total internal reflection at specificlocations is to provide waveguide 160 with upper surface portions thathave non-horizontal surface angles and/or scattering sites.Non-horizontal surface angles can allow light from within waveguide 160to refract out of waveguide 160 at specific angles. Alternatively,non-horizontal surface angles can reflect the light back into waveguide160 with a different internal angle than a horizontal angle, so that thereflected light is more susceptible to emission (e.g., no longer meetsthe total internal reflection criterion). Both of these techniques canbe useful, for example, to provide specific uplight distributions suchas an asymmetric or elliptical beam, or a “batwing” distribution havinghigh intensity light at specific angles with smaller portions of lightacross other upward angles. Scattering sites, too, can be configured tocause uplight to be emitted at certain angles, or can be random (e.g., arandom surface texture such as could be caused by sandblasting, etchingor the like) so as to provide emission of light across a distribution ofupward angles.

As shown in FIG. 3, luminaire 150 may be suspended from one or morecables 158 that can pass through waveguide 160 at any location, andadvantageously pass through waveguide 160 near a plan view center ofhousing 151. Cables 158 may, but do not necessarily need to, provideelectrical connectivity as well as mechanical support for luminaire 150.That is, electrical connectivity may be provided separately in someembodiments, for example through wires that drape loosely about cables158. In other embodiments, luminaires similar to luminaire 150 may besuspended using one or more rigid members (e.g., one or more stems) thatpass through a waveguide similar to waveguide 160, attaining the sameadvantages through the use of the waveguide.

In certain embodiments, apertures are formed through waveguide 160 (andreflector 168, if present) such that cables 158 do not mechanicallycouple thereto. These embodiments may include one or more means 170 fortransferring weight of luminaire 150 from a load bearing portion ofluminaire 150 to cable(s) 158, while providing strain relief for wiringwithin luminaire 150. For example, FIG. 3 shows two cables 158, eachbeing secured by a weight transferring means 170 at an underside of across member 157 that is formed by housing 151 and acts as the loadbearing portion. Housing 151 is not limited to the form shown; that is,other housing features besides a cross member can provide a load bearingportion. Weight transferring means 170 may be any of a stopper knotformed in each cable 158 and which cannot pass through apertures in theload bearing portion, a plug that secures a respective cable 158 andwhich cannot pass through apertures in the load bearing portion, a clampthat secures a respective cable 158 to the load bearing portion, orother suitable combination of these features, or mechanical equivalent.Thus, weight transferring means 170 transfers weight of luminaire 150 tocable(s) 158. When cables 158 also provide electrical connectivity forluminaire 150, weight transferring means 170 provide strain relief forwiring 156 that is located below the load bearing portion of housing151.

Numerous advantages may be obtained through the use of compact lightsources 162 such as LEDs, waveguide 160, and/or housing 151 to createand manage indirect light from luminaire 150. Such advantages mayinclude any or all of the following. (1) Waveguide 160 can act as anarea source of indirect light, which can spread out an apparent sourceof the indirect light for better viewing comfort, and greatly diminishany distracting shadows generated by cable(s) 158. (2) A height 190 ofhousing 151 can be significantly reduced in relation to a total height90 of housing 51 (FIG. 2). For example, a height 191 of the uplightportion of housing 151 may be as little as 5 mm. The reduced height ofhousing 151 is aesthetically pleasing and reduces material costs. (3) Ifsecond light sources 162 of different colors are used (e.g., red, greenand blue LEDs mixed to produce white, or white LEDs of different colortemperatures), waveguide 160 can act as a mixing chamber so that theprojected uplight is uniformly mixed, instead of producing localizedspots of one color or another. Additionally, for the configurationshown, (4) light sources 162 are placed at an increased distance fromlight source 152 so that heat from the two light sources is notconcentrated; (5) heat generated by light sources 162 can transferdirectly to an upper perimeter of housing 151, assisting further in heatdissipation; (6) by moving light sources 162 to the periphery of housing151, more area is provided near the center of housing 151 for electricalconnections, hanging features (e.g., stems, cables) and the like; and(7) by placing PCBs 164 and light sources 162 within a raised upperportion of housing 151, uplight provided by light sources 162 isprevented from emitting downwardly or outwardly, so that no features ofluminaire 150 that are illuminated by the uplight is visible from below.Still other advantages will be readily understood by one skilled in theart, upon reading and comprehending the present disclosure. As discussedbelow, other embodiments benefit from one or more of these advantages.

Optional reflector 168 can also provide various advantages. For example,reflector 168 can act as a heat spreader, to move heat from first lightsource 152 toward the periphery of housing 151 where the heat maydissipate to ambient air. When reflector 168 is not present, anunderside of waveguide 160 can be provided with a reflective (e.g.,metalized or painted) surface to ensure that light scattered byscattering features 166 exits through the upper face 161 of waveguide160.

FIG. 4 is a partially exploded, schematic view of luminaire 150 toassist in visualizing how certain components thereof relate to oneanother, and to provide additional description. Cables 158 are shown ashaving outer jackets 172, electrical wires 174, and a load bearing core176. Any of outer jackets 172, electrical wires 174, and load bearingcore 176 are optional, as long as at least one of such materials ispresent. That is, for example, electrical wires 174 could act as loadbearing materials of cables 158 without an outer jacket 172 and/or loadbearing core 176; similarly, cables 158 could consist solely of a loadbearing core 176 without an outer jacket 172 or electrical wires 174 (inwhich case, electrical connectivity would be supplied separately).Cables 158 pass through apertures 169 in waveguide 160, optionalreflector plate 168 (if present) and housing 151, where appropriatemechanical and/or electrical connections are made. PCB 164 is shown as asingle, strip-like (e.g., flexible) PCB curved into a circle, with lightsources 162 thereon. Wires 156 provide electrical connectivity for PCB164, extending into housing 151 (e.g., to interface electrically withcables 158 and/or first light source 152). The use and compact form ofPCB 164 and light sources 162 with waveguide 160 (with optionalscattering features 166 on an underside thereof) enables simple assemblyof luminaire 150. Although PCB 164 is shown as a single PCB, thefunctionality provided by PCB 164 could be provided by two or more PCBs.PCB 164 may be secured in any manner, such as mechanically (e.g., withscrews or other fasteners, interference or snap fitting) and/or usingadhesives. Covers and/or coatings may be utilized to protect PCB 164and/or light sources 162.

FIG. 5 is a schematic cross-sectional view illustrating adirect/indirect luminaire 250. Luminaire 150 includes a housing 251, anda first light source 152 and first optics 154 that are substantiallysimilar to first light sources and optics shown in luminaires 50 and150. Indirect light (e.g., uplight) is supplied by second light sources262 that are mounted with one or more PCBs 264. Similar to housing 151and luminaire 150 (FIGS. 3 and 4), housing 251 and luminaire 250 arecylindrical in aspect, but this is not required.

In luminaire 250, housing 251 includes an inner portion 258 that isbounded on all sides by a horizontal portion 257. Inner portion 258 mayprotrude upwardly relative to horizontal portion 257, but this is notrequired. Light sources 262 (which may be, for example, light emittingdiodes (LEDs) in packaged or chip form) mount to one or more PCBs 264,which may be flexible PCB(s) affixed to inner portion 258. Light sources262 emit light that couples into a waveguide 260 that forms at leastpart of an uppermost optical surface of luminaire 250. Like waveguide160 (FIGS. 3 and 4), waveguide 260 is a planar portion of an opticalmaterial (e.g., glass, polycarbonate, acrylic, other plastics, silicone)with opposing planar faces 261 and 263. Waveguide 260 forms an aperture269 with a clearance to accommodate inner portion 258, and the opposingplanar faces 261 and 263 are joined by edge faces 267 of the aperture.That is, there may be vertical edge faces 267 where waveguide 260 faceslight sources 262, but outer edge faces 265 of waveguide 260 could berounded or some other shape, as the outer edge faces 265 are not lightcoupling surfaces. When inner portion 258 protrudes upwardly fromhorizontal portion 257, and the inner edge 267 of waveguide 260 isvertical, second light sources 262 may be in face to face relation withthe inner edge, as shown. However, again, this is not required; innerportion 258 need not protrude upwardly, second light sources 262 may notbe oriented as shown, and may not be in face to face relation with theinner edge 267. One skilled in the art, upon reading and comprehendingthe present disclosure, will readily conceive of many alternatives andequivalents. The light that couples into waveguide 260 is substantiallyretained therein through total internal reflection, except at scatteringfeatures 266, similar to scattering features 166 described above.Scattering features 266 are shown arranged in a distribution with morescattering features 266 near the outer edges of waveguide 260, and fewerscattering features 266 near second light sources 262, to compensate forlight density within waveguide 260 being greater nearer second lightsources 262. However, this distribution is only exemplary; those skilledin the art will be able to provide variations on this layout to serveaesthetic and/or functional needs of a given application. An optionalreflector 268 may be included; these elements are similar in function toreflector 168, FIGS. 3 and 4, but may be different in layout, toaccommodate inner portion 258. Thus, at least a portion of the lightthat is emitted into waveguide 260 emits upwardly from housing 251 andluminaire 250.

Cable 158, weight transferring means 170 and wiring 156 are similar tolike items shown in luminaire 150. Because light sources 262 emitoutwardly from the inner portion of housing 151 toward its edges, theuplight portion luminaire 150 can be thought of as a “center-firing”arrangement as opposed to the “edge-firing” arrangement illustrated inFIGS. 3 and 4.

FIGS. 6-10 are schematic cross-sectional views illustrating portions ofrespective direct/indirect luminaires. These drawings illustratetechniques that can be adapted to produce a variety of functions andvisual effects. Upon reviewing FIGS. 6-10, and reading and comprehendingthe following explanations, one of ordinary skill in the art willreadily conceive many equivalents, extensions, and alternatives to thespecific, disclosed luminaire features and types, all of which arewithin the scope of embodiments herein.

FIG. 6 schematically illustrates a direct/indirect luminaire 350 thatincludes a waveguide 360 with upward protrusions 362. Luminaire 350includes the same housing 251, PCB(s) 264 and light sources 262 asluminaire 250, FIG. 5. Upward protrusions 362 are shown at radiallyoutside edges of waveguide 360, and with rounded upper ends, butprotrusions 362 may be located and/or shaped differently. In particular,shape(s) of protrusions 362 may be modified so as to direct portions ofthe uplight from second light sources 262 in desired directions. Forexample, the rounded ends shown in FIG. 6 will encourage all lightreaching the rounded ends to exit waveguide 360, such that the end willappear bright in a direct view and will emit the light in alldirections. Luminaire 350 is shown without a reflector and/or scatteringfeatures below waveguide 360; similar to the case noted for luminaire150, an underside of waveguide 360 can be provided with a reflective(e.g., metalized or painted) surface to encourage light to exit throughthe upper surface of waveguide 360, and/or protrusions 362.

FIG. 7 schematically illustrates a direct/indirect luminaire 450 thatincludes a waveguide 460 having outward protrusions 464 that extendthrough a housing 451, so as to emit a portion of light outwardlytherefrom, providing visual interest. Luminaire 450 includes the samePCB(s) 264 and light sources 262 as luminaires 250 and 350, FIGS. 5 and6, emitting light into waveguide 460 from an inner portion 458 ofhousing 451, in a center-firing arrangement. However, housing 451 allowsoutward protrusions 464 of waveguide 460 to extend therethrough. Outwardprotrusions 464 as illustrated in the cross-sectional view of FIG. 7 maybe a single, radial protrusion, in which case an uppermost portion 452may not be contiguous with housing 451 but form a separate element thatcan be fastened to waveguide 460 with adhesives or the like.Alternatively, outward protrusions 464 may be azimuthally intermittentabout a periphery of waveguide 460; that is, outward protrusions 464 maybe features that extend through corresponding apertures of housing 451.

FIG. 8 schematically illustrates a direct/indirect luminaire 550 thatincludes waveguide 460 with outward protrusions 464 (the same waveguideas in luminaire 450, FIG. 7) and upper housing portions 552, 554.Luminaire 550 includes the same PCB(s) 264 and light sources 262 asluminaires 250, 350 and 450, FIGS. 5, 6 and 7, emitting light intowaveguide 460 from an inner portion 558 of housing 551, in acenter-firing arrangement. Like housing 451 of luminaire 450, housing551 also allows outward protrusions 464 to extend therethrough, so as toemit a portion of light outwardly therefrom, providing visual interest.Housing 551 also includes upper housing portions 552 and 554, as shown,to demonstrate variations in housing shapes. On the left hand side ofFIG. 8, upper housing portion 552 covers an upper surface of waveguide460 such that (in the cross-sectional portion shown) light from lightsource 262 would be emitted only through outward protrusion 464. On theright hand side of FIG. 8, upper housing portion 554 only partiallycovers an upper surface of waveguide 460 such that (in thecross-sectional portion shown) some light from light source 262 may beemitted through outward protrusion 464 while other light from lightsource 262 may be emitted through the uncovered upper surface ofwaveguide 460. It is not required to arrange upper portions of a housingexactly as shown in FIG. 8; housing portions 552 and 554 are shown onlyto explain possible features that can be rearranged to achieve a desiredlight distribution and/or for visual interest.

FIGS. 9 and 10 are schematic cross-sectional views illustrating portionsof direct/indirect luminaires that do not include waveguides. Thesedrawings illustrate techniques that can be adapted to produce a varietyof functions and visual effects. Upon reviewing FIGS. 9 and 10, andreading and comprehending the following explanations, one of ordinaryskill in the art will readily conceive many equivalents, extensions, andalternatives to the specific, disclosed luminaire features and types,all of which are within the scope of embodiments herein.

FIG. 9 schematically illustrates a direct/indirect luminaire 650 thatincludes an optic 660. Luminaire 650 includes the same housing 151,PCB(s) 164 and light sources 162 as luminaire 150, FIGS. 2 and 3, butmodifications are possible, as discussed below. Optic 660 can beprovided with specular or diffuse surfaces to redirect light from lightsources 162, without or with diffusion, respectively. For example,Lambertian, “batwing,” elliptical or asymmetrical distributions can beprovided. PCBs 164 and light sources 162 need not be positioned exactlyas shown in FIG. 9; also, changes to the housing shown are possible(e.g., center-firing arrangements, as shown in FIGS. 5-8, may be used).Optic 660 may be adapted to provide protection for PCB 164 and/or lightsources 162, and covers and/or coatings may also be utilized to providesuch protection. FIG. 10 schematically illustrates a direct/indirectluminaire 750 that can optionally include PCB(s) 764 with light sources762, and/or PCB(s) 768 with light sources 766. Any number, combinationor arrangement of the PCB(s) and light sources shown in FIG. 10 may beused. Luminaire 750 also includes the same housing 151 as luminaires 150and 650, FIGS. 2, 3 and 9, but modifications are possible. Luminaires650 and 750 represent very low cost and compact alternatives toproviding uplight from a luminaire.

FIG. 11 schematically illustrates a direct/indirect luminaire 850including a waveguide 860 that obtains light from a downlight source852, and redirects a portion of the light to provide uplight. A housing851 provides mechanical support for the components shown. Electricalinterconnection is not shown in FIG. 11 for illustrative clarity, butcan be provided in similar manner to that shown in FIGS. 3-5 discussedabove. A light source 852 provides light for both uplight and downlightpurposes; an optic 854 can redirect a portion of the light from lightsource 852 to provide downlight, while scattering features 866 ofwaveguide 860 redirects another portion of the light from light source852 to provide uplight. Portions of waveguide 860 may be externallycoated with a reflective material (e.g., a metalized coating) toincrease transmission efficiency of waveguide 860 to an upper surface ofluminaire 850. Also, waveguide 860 may be provided in multiple piecesfor assembly purposes. For example, a break in waveguide 860 may occurat location 861 shown in FIG. 11, so that upper and lower portions ofwaveguide 860 can be assembled separately. Luminaire 850 includes cables158 and optional reflector 168 as in luminaire 150, FIGS. 2 and 3, toshow that such components could be used, but these components can berearranged, substituted or omitted, as would be apparent to one skilledin the art upon reading and comprehending this disclosure.

The foregoing is provided for purposes of illustrating, explaining, anddescribing embodiments of the present invention. Further modificationsand adaptations to these embodiments will be apparent to those skilledin the art and may be made without departing from the scope or spirit ofthe invention. Different arrangements of the components depicted in thedrawings or described above, as well as components and steps not shownor described, are possible. Similarly, some features and subcombinationsare useful and may be employed without reference to other features andsubcombinations. Embodiments of the invention have been described forillustrative and not restrictive purposes, and alternative embodimentswill become apparent to readers of this patent. Accordingly, the presentinvention is not limited to the embodiments described above or depictedin the drawings, and various embodiments and modifications can be madewithout departing from the scope of the claims below.

What is claimed is:
 1. A luminaire, comprising: a housing; a downlightthat includes one or more first light sources configured to emit a firstlight downwardly from the housing; a waveguide, formed of an opticalmaterial and comprising opposing faces joined by one or more edge facesabout a periphery of the optical material, the waveguide forming atleast a portion of an uppermost optical surface of the luminaire, anddefining an aperture therethrough; one or more second light sources,coupled with the housing and configured to emit a second light into theoptical material through at least one of the one or more edge faces, anda cable configured to provide electrical power to the first and secondlight sources: wherein: the waveguide is configured to emit at least aportion of the second light upwardly from an upper one of the opposingfaces; and the cable extends through the aperture.
 2. The luminaire ofclaim 1, wherein: the housing forms a cylinder; the one or more firstlight sources are disposed within the cylinder; and the one or moresecond light sources couple with an inner surface of the cylinder. 3.The luminaire of claim 1, wherein the one or more second light sourcesare light emitting diodes coupled with an inner periphery of thehousing.
 4. A luminaire claim 1, comprising: a housing, wherein thehousing forms a horizontal portion, and an inner portion that extendsupwardly from the horizontal portion, the inner portion being bounded onall horizontal sides by the horizontal portion; a downlight thatincludes one or more first light sources configured to emit a firstlight downwardly from the housing; a waveguide, formed of an opticalmaterial and comprising opposing faces joined by one or more edge facesabout a periphery of the optical material, the waveguide forming atleast a portion of an uppermost optical surface of the luminaire,wherein: the waveguide defines an aperture therethrough, and theaperture provides a clearance about the inner portion and defines atleast one inner edge face of the one or more edge faces of the opticalmaterial; one or more second light sources, coupled with the housing andconfigured to emit a second light into the optical material through atleast one of the one or more edge faces; and wherein: the waveguide isconfigured to emit at least a portion of the second light upwardly froman upper one of the opposing faces, and the one or more second lightsources are coupled with the inner portion, and emit the second lightinto the at least one inner edge face of the optical material.
 5. Theluminaire of claim 4, wherein: the inner portion protrudes verticallyupward relative to the horizontal portion; the at least one inner edgeface of the optical material is substantially vertical; and the one ormore second light sources are oriented in face to face relation with theat least one inner edge face.
 6. The luminaire of claim 1, wherein thecable extends through a load bearing portion of the housing; theluminaire further comprising means for transferring at least part of aweight of the luminaire from the load bearing portion to the cable,while providing strain relief for wiring within the luminaire.
 7. Theluminaire of claim 6, wherein the means for transferring at least partof the weight of the luminaire comprises: a stopper knot in the cable; aplug fixedly coupled with the cable, wherein the plug cannot passthrough the load bearing portion; or a clamp that fixedly couples thecable with the load bearing portion.
 8. The luminaire of claim 1,wherein the cable is one cable of a plurality of cables, and wherein:the waveguide defines a plurality of apertures therethrough, theplurality of apertures being equal in number to the plurality of cables;and each of the plurality of cables extends through a corresponding oneof the plurality of apertures.
 9. The luminaire of claim 1, wherein alower one of the opposing faces of the waveguide is configured toscatter the portion of the second light upwardly.
 10. The luminaire ofclaim 1, further comprising a reflector disposed beneath the waveguide.11. The luminaire of claim 10, further comprising a cable configured toprovide electrical power to the first and second light sources, andwherein: the reflector forms an aperture therethrough; the aperturethrough the waveguide aligns vertically with the aperture through thereflector; and the cable extends through both of: the aperture throughthe waveguide; and the aperture through the reflector.
 12. A method oflighting an area with a suspended luminaire, comprising: providing aluminaire that includes a housing, a first light source, one or moresecond light sources, and a waveguide that forms at least a portion ofan uppermost optical surface of the luminaire, wherein the waveguide isformed of a portion of an optical material and characterized by opposingplanar faces joined by one or more edge faces about a periphery of theoptical material; suspending the luminaire from a cable that passesthrough the waveguide; emitting a first light downwardly from the firstlight source; emitting a second light, from the one or more second lightsources, into one or more of the edge faces of the waveguide; andscattering at least a first portion of the second light upwardly fromthe waveguide, through an upper one of the planar faces.
 13. The methodof claim 12, wherein providing the second light comprises providing thesecond light sources arranged in face to face relation with the one ormore of the edge faces of the waveguide.
 14. The method of claim 12,wherein providing the second light comprises scattering the firstportion of the second light from scattering features on a lower one ofthe planar faces.
 15. The method of claim 12, wherein providing thesecond light comprises reflecting a second portion of the second lightfrom a reflector disposed beneath a lower one of the planar faces. 16.The method of claim 12, wherein suspending the luminaire comprisessecuring the housing to the cable so as to transfer at least part of theweight of the luminaire to the cable, while providing strain relief forwiring within the luminaire.
 17. A method of lighting an area with asuspended luminaire, comprising: providing a luminaire that includes: ahousing, a downlight that includes one or more first light sourcesconfigured to emit a first light downwardly from the housing, one ormore second light sources, and a waveguide that forms at least a portionof an uppermost optical surface of the luminaire, wherein: the housingforms a horizontal portion, and an inner portion that extends upwardlyfrom the horizontal portion, the inner portion being bounded on allhorizontal sides by the horizontal portion, the waveguide is formed of aportion of an optical material and characterized by opposing planarfaces joined by one or more edge faces about a periphery of the opticalmaterial, the waveguide defines an aperture therethrough, and theaperture provides a clearance about the inner portion and defines atleast one inner edge face of the one or more edge faces of the opticalmaterial; the method further comprising: emitting a first lightdownwardly from the one or more first light sources; emitting a secondlight, from the one or more second light sources, into the at least oneinner edge face of the optical material; and scattering at least a firstportion of the second light upwardly from the waveguide, through anupper one of the planar faces.